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As vehicle owners, we assume our vehicles will be reliable. We trust that the brakes will stop the car, every time. Most people don’t really question how the brakes work. Leave that to the engineers. After all, we paid a lot of money for this assumed sense of security.

That’s a potentially life-changing failure of a system we don’t really pay attention to.

That’s why I’d like you to know more about how this crucial system works and the threats it faces over time and miles.

The rhinoceros and the armor

At a glance, your brake system doesn’t seem too complex. Hit the pedal, the car stops, simple. But the brakes are one of the hardest working systems of your vehicle. They have to be able to stop a 2-ton car in a matter of seconds. That’s like stopping a charging rhino dead in his tracks. Pretty impressive if you ask me (also terrifying). Considering the tremendous amount of friction it takes to accomplish this, it’s no surprise that your brake fluid takes a beating.

Like the rhino, brake fluid has a coat of armor to protect it. All brake fluids have additive packages. Some are much better than others (cough-BG-cough-cough). Additive packages include some pretty powerful players like: corrosion inhibitors, anti-wear, and antioxidants. These all seem like complicated, science-y words, but trust me (I’m a scientist), these additives are crucial to the reliability of your brakes.

Without armor, the brake system is vulnerable to… dun-dun-dunnn… BRAKE KILLERS!

Every time you press the brake pedal, you increase heat in the brake system (high friction=high heat). This heat causes the brake fluid to expand. When it cools and contracts, it draws in outside air. Humidity in the air brings moisture into the system.

Why is this a problem? Because, brake fluid is hygroscopic. That’s just a fancy (science-y) word meaning it likes water. On a molecular level, brake fluid attracts moisture. As moisture builds up in your brake fluid, the boiling point decreases. If your fluid can’t tolerate high heat, it’s less likely to do a good job protecting the brake components.

The brake lines in your vehicle contain copper. Copper is highly susceptible to oxidation, meaning it will corrode, or break down, when exposed to oxygen. Your brake fluid’s armor (the additive package) protects against corrosion for a matter of time. But heat, driving conditions, and extreme temperatures eventually take their toll on these additives.

When the additives are depleted, your brake fluid starts to degrade. Over time, the small amounts of air and water entering the brake system cause copper corrosion. And this leads to copper contamination of the brake fluid.

Yes, you read that right. Time is a brake killer.

Think of it like this: Most runners don’t wear the same shoes until they’ve worn the soles off. (Unless they’re being chased by a 2-ton rhino, in which case, who has time for changes in footwear?) A smart runner replaces running shoes when the support and stability are starting to fade. Same goes for brake fluid. When the armor stops protecting the fluid and copper corrosion becomes too high, that means brake fluid isn’t functioning as it should anymore. It’s time to replace it.

The brake system works hard. Stopping a rhino in its tracks multiple times a day, every day, seems like it would be tough work (not that I’d know first hand). Brake fluid wasn’t made to be destroyed. It was made to do its job until it can’t anymore. And when that happens, you get new brake fluid (about every couple years).

Remember: An educated driver is a safe driver!

by Michael Belluomo
Technical Service Manager
30 years of experience in fuel and lube technologies